Typically, during semiconductor device manufacturing, a vapor deposition process is utilized to deposit materials along fine lines or within vias or contacts on a silicon substrate. The vapor deposition processes can include thermal chemical vapor deposition (TCVD) or plasma enhanced chemical vapor deposition (PECVD). In PECVD, plasma is utilized to alter or enhance the film deposition mechanism. For instance, plasma excitation generally allows film-forming reactions to proceed at temperatures that are significantly lower than those typically required to produce a similar film by TCVD. In addition, plasma excitation may activate film-forming chemical reactions that are not energetically or kinetically favored in thermal CVD. The chemical and physical properties of PECVD films may thus be varied over a relatively wide range by adjusting process parameters.
More recently, atomic layer deposition (ALD) and plasma enhanced atomic layer deposition (PEALD), which are forms of CVD or more generally film deposition, have emerged as a candidate for ultra-thin gate film formation in front end-of-line (FEOL) operations, as well as ultra-thin barrier layer and seed layer formation for metallization in back end-of-line (BEOL) operations. In ALD, two or more process gases are introduced alternately and sequentially in order to form a material film one monolayer (or less) at a time. Such an ALD process provides a self-limiting characteristic which has proven to provide improved uniformity and control in layer thickness, as well as conformality to features on which the layer is deposited. As in PECVD, PEALD processing is utilized to alter or enhance the film deposition mechanism. However, current PECVD and PEALD processes often suffer from contamination problems that affect the quality of the deposited films and the interfaces between the PECVD or PEALD films and other films in a manufactured device. Further, exposure of a substrate to a plasma can damage sensitive areas of a substrate. Thus plasma enhanced processes may be undesirable in some situations, and alternative processing methods are needed for improving the properties and integration of films in semiconductor devices.